Method for reversely planning treatment plan and treatment plan system

The invention discloses a method for reversely planning a treatment plan. The method comprises the following steps of: A, inputting a medical image of a patient; B, drawing the tissue profiles of the body surface of the patient, a target body and organs at risks; C, setting a reserve planning target; D, establishing an initial treatment plan; E, setting an iterative optimization parameter; F, generating an individual treatment plan; G, computing an individual treatment plan dose field; H, computing the degree of adaptability; I, selecting a current optimal plan; J, if evolution times are greater than population evolution times, turning to a step M, or otherwise turning to a next step; K, evolving a population to a new generation of population and turning to the step G; and M, stopping population evolution and outputting a current optimal plan. The invention also discloses a treatment plan system. A method for computing the degree of adaptability is used for selecting an optimal plan, so that the evolution efficiency of the population can be increased, and an optimizing process is efficient.